Confined assembly of ultrathin dual-functionalized Z-MXene nanosheet intercalated GO nanofilms with controlled structure for size-selective permeation

The development of lamellar membranes with specific two-dimensional (2D) structures for efficient separation is highly desired. However, the rational design of ultrathin 2D/2D lamellar membranes with controlled structure and components still remains a great challenge. Herein, we report a general and low cost route for large-scale preparation of zwitterionic MXene (Z-Mxene) nanosheet intercalated GO nanofilms with size-selective permeability via an alignment oriented slow deposition method. By means of tunable ligand conformation and favorable hydrophilicity of dual-functionalized Z-MXene, multicomponent lamellar nanofilms with dual and ordered nanochannels in confined spacing were achieved. The strong interactions between GO and Z-Mxene nanosheets prevented the existing self-restacking phenomenon in conventional membrane fabrication which severely hindered mass transport. Moreover, the introduction of zwitterionic MXene into a composite membrane significantly improved the distribution of surface functional groups; the uneven distribution problem of surface functional groups and the harmful issues of nanochannel contortions can be effectively avoided. These favorable characteristics together with surface chemistry endowed the prepared composite membranes with strong hydration capacity, high permeability, low fouling propensity and distinctive stability. These improved properties suggest a promising way to develop multicomponent nanofilms with precisely controlled composition and structure for vast applications.